Method of cutting duct sections



c. F. ENGEL 2,648,381

METHOD OF CUTTING DUCT SECTIONS Aug. 11, 1953 2 Sheets-Sheet l Filed March 23, 1950 @fff JNVENToR. CHARLES FRANK ENGEL Aug. 11`, 1953 c. F. ENGEL 2,548,381

METHOD OF CUTTING DUCT SECTIONS .Filed Maron 23, 195o l 2 sheets-sheet 2` III llllllllllvlllllllvlul 22 INVENTOR.

CHARLES FR ANK ENGEL,

UNl

arrasa ME'lllllD @F GTUlrllllNG DUCT SEC'IENS (Charles liranlr Engel, St. Louis, Mio.

Application March 23, i950, Serial No. ili'lll (Cl. 16d-i7) SClairns. l.

This invention relate to improvements in methods for measuring, cutting and notching sheet metal fo1 orining four-sided ducting, as used for heating and air-conditioning installations.

Straight sections of ducts for the purposes aforementioned are usually bent from individual sheets of metal. Such straight sections are normally interconnected by transition sections, that is, pieces of duct Whose crosssections vary along their length, required to carry over or under beams, to allow branching or the duct systems, to change cross-sectional area, and for other familiar purposes. These transitional sections are norrnally made from four ilat pieces of sheet metal, one pair or which have soine curved edges and the other pair being rectilinear and bi-syininetric but normally cut at oblique angles. rEhe inherent variations in structure, form, length and proportion of the sheet nietal pieces required. for a single installation have heretofore been generally considered too great to achieve mass production. Instead, it has been the practice to lay out ducts individually, measuring and punch-rnar ing the location of each shearing cut, bend and corner, shearing the material on sanare shears, and cutting corners and notching the material for bends by' hand.

It should be explained that, according` to conventional practice, the corners or ducts must be notched before they are formed so that inaterial may be bent back at each end or the duct to forni flanges for the connection of adjacent duct sections. Further, Where a linear seam is required along a duct (as in forming a straight duct section after bending a sheet with three parallel rectangular bends) the corners to be fed into a searning machine, such as a Pitts burgh machine, must be first notched to permit acceptance into and forming by such inachine.

It is an object ci this invention to create inethods for the quick and inexpensive manufacture of uniform interchangeable four-sided ducts, both straight and transitional sections.

Another object is to provide nieans and mechanisms for measuring, shearing, laying out and notching duct sheet.

Another object is to provide adjustable stops and abutments to serve in shearing duct sheet at oblique angles as Well as at right angles, and also in notching duct sheet at oblique angles.

Another object is to provide a rectangular measuring table equipped with adjustable guide stops and with rolling shear means operable along the entire length of tWo adjacent sides thereof.

Another object is t provide novel shearing roll cutters operable along two adjacent edges of a rectangular table and adapted to shear sheets of any length.

Another object is to provide a duct making device with a removable plurality of adjustably spaced cam-operated notching cutters.

additional objects include equipping such duct nialring device with linear and protractor scales to cooperate with the several tools incorporated in such device.

A further object is to provide a niethod and means for mechanically notching loi-symmetric duct sheets to locate their corners and bends.

L'n the drawings:

Fig. l is a plan view of a duct jig embodying my invention.

Fig. 2 is a fragmentary detail taken in section on line 2 2 of Fig. 1.

3 is a fragmentary detail View in plan talren along line 3 3 or Fig. 2.

Fig. is a perspective View of a polygonal side element of a -piece section of transition ducting, sheared and notched according to a possible set-up of my invention shown in Fig. l.

Fig. 5 is a fragmentary perspective View of one end oi a sheet sheared and notched to form a section of onepiece rectangular ducting.

Fig. 6 is a fragmentary detail View in elevation taken along line e-e of Fig. l.

Fig. 'I is a sectional View taken along line i- 3 Of Fig. 6.

Fig. 8 is a fragmentary View, partly in elevation and partly in section, taken along line 8--8 oi Fig. 1.

Fig. 9 is a fragmentary elevation taken along line i'-Q ci Fig. l.

Fig. lll is a fragmentary sectional View taken along line lll-i@ oi Fig. l.

Fig. ll is a fragmentary View, partly in elevation and partly in section, along line li-H of Fig. l.

Fig. l2 is a fragmentary View, partly in elevation and partly in section, taken along line iZ-l 2 of Fig. 11.

ln the ch is of iron traine and legs 23. Rising from the baci; edge o table plate 2i is abutment strip 2li, secur to traine 2;? by screws and scribed with linear scale M Whose graduations relate to cnt illustrated, steel table plate the outer edge 21 of shear guide angle 28. Said shear guide angles upper horizontal surface is on the same plane as table plate 2| and is in effect an extension thereof, being butted against its edge and secured by countersunk screws 29 to the outstanding edge 39 of tie plate 3|, welded beneath table plate 2| outward of supporting frame 22. However, said shear guide angle 28 continues rearward of table plate 2| to form right hand shear base 32, as shown in Fig. 1.

The forward edge is similarly constructed, commencing with forward outer edge 21 of shear guide angle 28', which is similarly affixed by countersunk screws 29' to the forward outstanding edge 39 of a forward extending tie plate 3| welded beneath the forward edge of the table plate 2|. Shear guide angle 2B extends beyond the right edge of table plate 2| to form forward shear base 32'. Graduated from forward outer edge 21 and extending rearward are linear scales 33, scribed in the surface of table plate 2 Operable from said shear bases 32 and 32 and along shear guide angles 28 and 23 respectively are the right hand rolling shear 34 and the forward rolling shear 34', shown in detail in Figs. 6 and '1. Each of these shears has a carrier 35 shaped generally like an inverted channel, having a straight inner flange 36 of uniform depth. The outer flange 31 of frame 35 varies in depth, however. At the forward end 38 of said carrier, outer flange 31 is of the same depth as inner flange 33, but aft of said forward end 38 its depth increases for the purposes and in the manner hereinafter described.

Housed between carrier flanges 36 and 31 near forward end 38 of each of the shear carriers 35, so as to protrude but slightly below said flanges, is forward roller 39 and upper shearing disc 40, rotatably mounted on thread-ended pin 52, which has provision for lateral adjustment hereinafter described and is mounted normal to flanges 3S and 31. Shearing disc 4B has at its inner side (that is, inward with relation to table plate 2|) a tubular stem portion 43 whose bore is sufllciently greater than the diameter of stem |22 to permit free rotation thereon, and at its outer side a tapered blade 44, whose diameter is a maximum at its outer or cutting edge 45, the diameter of said edge being equal to the outer diameter of roller 39, or nearly as great. The bore 46 of forward roller 39 is such as to permit easy rotation about the outer surface of the tubular stem portion 43 of said shearing disc 49.

Between flanges 36 and 31 near the aft end 41 of carrier 35 is housed aft roller 48, being of the same diameter but having greater width than forward roller 39, and being rotatably mounted on a bolt 4| (secured by a nut 42) through a bore normal to said flanges and at the same height as the axis of the forward roller 39 and shearing disc 45, so that forward roller 39 and aft roller 48 are substantially in alignment with each other.

Inasmuch as the cutting or shearing of the sheet metal is to be done from the forward end of carrier 35 by shearing disc 49 and a mating shearing disc 53 whose axis is below the surface of table plate 2|, the outer flange 31 of carrier 35 is enlarged downward at the aft end 41 of the carrier 35, sufficiently so that when rollers 39 and 48 rest on vguide angle 28, said aft end of outer flange 31 will extend below said guide angle 28. A rigid mating angle 49, adapted to engage slidingly the inner face of the guide angle 28 and cause its outer face slidingly to engage the aft end of said outer flange 31, is affixed on the' inward side of said aft end of outer flange 31 by bolts 50. Forward of the point of afxation, the lower edge of said outer flange sweeps upward and forward to form a guideway 5| which merges gradually into the horizontal at a point beneath the axis of the upper shearing disc 40.

Vertically beneath and parallel to said axis, thread-ended pin 52 is mounted in and expandsoutward from mating angle 49. Rotatably mounted on said pin as an axis is lower shear-- ing disc 53, which is identical with upper shearing disc 49 but faces inward instead of outward.. The location of said lower shearing disc 53 isr such that its cutting edge 45 is laterally in contact with the corresponding cutting edge of the upper disc, and reaches a vertical height slightly' above the lowest point of the cutting edge onv said upper disc in relationship suitable for shearing.

A guard channel 54 whose flanges 55 extend inward and are tapered at their inner ends 56, ts closely adjacent the lower shearing disc 53, in respect of the relation of inner flange ends 56 to the cutting edge 45 and also in respect of the relation of the outer end of tubular stem portion 43 with the base of said channel 54. Free rotation is achieved by the interposition of ball bearing surrounding tubular stem portion 43 between said channel base and the blade 44. Said guard channel 54 is held in position by two nutfltted studs mounted in mating angle 49 on each side of lower shearing disc 53 and penetrating bores through the base of channel 54 in registration with said Studs. Aft of the axis of thread-ended pin 52, the upper flange of said guard channel 54 is curved backward and downward corresponding to the curvature of the adjacent portion of guideway 5|.

An operating handle 59 is affixed to and projects upward from carrier 35.

The manner of using said rolling shears 34 and 34' will be at once apparent. Between cutting operations they are permitted to stand on shear bases 32 and 32 at the outward-extending ends of guide angles 28 and 28', their outward movement being limited by stops 60 and 63. The interaction of said shears with other features of my invention require some additional explanation, however.

In order to secure large sheets of metal while they are being sheared, I provide toggle clamps 6|, each of which comprise an arm 62 and elbow 63 swngably mounted in bracket 64 affixed to the rear 0f frame 22. At the forward end of arm 92 is a vertical bore 65 within which shaft 95 is operable reciprocatingly by toggle mechanism 61, its downward movement being resisted by the force of compression spring Evagainst cap E9 at the top of shaft 66. At the lower end of shaft 65 is afxed clamp pad 10, which is adapted to clamp and hold sheet metal sheets against table plate 2|. When not in use, said toggle clamps 8| may be swung out of the way, as shown in phantom in Fig. 1.

rIable plate 2| is provided with a plurality of fore-and-aft slots 1| arranged in pairs, terminating at their aft end in enlarged circular holes 12. For each pair of slots is provided one or more abutment bars 13 of rectangular cross-section of a length substantially greater than the distance between a slot and its paired slot. Each of said abutment bars 13 is provided with two short vertical slots 14 along the longitudinal axis of said bars, the adjacent ends 15 of which slots 71| are no farther separated than the distance between the parallel slots li in connection with which they are used. Said slots 'H and lll are of such width as readily to accommodate and permit sliding motion of carriage-head bolts 16, but smaller than the heads Vi thereof. As shown in Figs. 1 and 10, the heads 'il of said carriagehead bolts are inserted downward through enlarged holes 'f2 upon loosening (but not removing) wing nuts l0, which can be tightened against washers l tc fix said abutment bars 'I3 on the surface of table plate 2| in any desired fore-andaft and angular' position, within the limits of movement permitted by said slots and itl.

One use for abutment bars llty is to set them parallel to the forward edge of table plate 2| at a distance determined from linear scales 33, and to thus utilize them as an abutment and guide for cutting long sheets into desired widths with the forward shear 3d. Another use is illustrated at the right side of Fig. 1, in conjunction with angular abutment t0, which will now be described.

Said angular abutment comprises two substantially parallel horizontal rods 3| and 0i extending laterally from the frame 22. On rods 8| and 8i are sliding sleeves d2 and 82 respecn tively, each having on its under side a tapped hole 83 and thumb screw til; on their upper sides are vertical pins 85 and 05 respectively. On

pin 85 is attached one end of a short link Bt, whose other end bears vertical pin al. Said pin d'1 is attached through the horizontal flange 88 of angle 09, whose upturned vertical flange 90 faces table plate 2| and, as shown in Fig. 6, eX- tends from slightly below to slightly above the plane of said plate.

Angular abutment 00 is of especially valuable use in cutting uniform `loi-symmetric :dat pieces at oblique angles for transition section faces, such as shown in Fig. li. Having rst utilized abutment bars 73 to cut the sheet metal to the necessary width, two such abutment bars are set up parallel to each other and spaced apart the width of the sheet strips in the fore-and-aft slots 1| adjacent the right end of table plate 2| at such degree of angularity to shear guide angle as is required. The requisite angularity may be determined from a pattern or by reference to the protractor 9| scribed in the right edge of said table plate. The sheet strip to be cut is then fed between said abutment bars 'f3 slightly past shear guide angle 28, and trimmed with a forward movement of right hand rolling shear 34. The sheet strip is turned over, so that the edge formerly nearer the operator is now the farther edge, and then advanced between said abutment bars sufficiently so that a stroke of shear 34 would cut it to proper size. The angular abutment 80 is then adjusted by sliding the sleeves 82 until vertical flange 90 of the abutment is hush against the edge of the as yet uncut piece, and the thumb screws 85| tightened. The piece is then cut and removed, the strip again turned over and advanced against vertical fiange 90 as an abutment, and cut, and the process repeated until as many pieces as desired have been cut or the strip is exhausted. The angular abutment 8@ is in function a remote gage adjustably located as to space and angle from the rectilinear shear line formed by the path of the rolling shear 34.

Notching of the duct sheets is accomplished at the left edge of the device. Bolted to frame 22 along the left side and somewhat below the plane of table plate 2|, by nut-tted bolts 92, is inner notcher support bar 93, which is paralleled by outer notcher support bar 94. These extendthe entire depth of table plate 2|, and are held in alignment with reference to each other by end fittings 95 at their forward and aft ends, said end fittings being aihxed by screws St penetrating them and entering tapped holes 97 in the ends of said bars 93 and gli. The upper portions 98 of said end fittings 95 contain large fore-andaft horizontal bearing bores which support the fore-and-aft ends of an eccentric-mounted rod EGG, rotatable therein as a cam by applying torque by means of handle |0 A plurality of notchers may be adjustablyand removably aflixed to outer notcher support bar 94, so as to bear upon both it and inner support bar 93. Such a notcher is shown in detail in Figs. 2 and 3. It comprises a block |02 adapted at its inner side to rest atop inner notcher sup-l port bar 93, and having at its outer side a de pending portion |03 with a central square-cut keyway |04 of such size as to accommodate and bear upon outer notcher support bar 94, permitting the sliding of block |02 along said support bars except when restrained by turning and ad' vancing thumb screw |05 through tapped holel |06 penetrating sideward into keyway |04, and tightening it against outer notcher support bar 943.

Notcher block |02 has a horizontal throat |01 cut from front to back adjacent to table plate` 2| and of sufficient depth to accommodate the' thickness of the sheet metal to be processed.. The lower side ldd of said throat |07 is in the same plane as said table plate 2|. The left margin or abutment |09 of said throat |0'| serves as a stop for sheet metal inserted therein; and the insertion of such sheet metal into throat- 10i is facilitated by the curved entrant portion ||0.

Referring still to Figs. 2 and 3, block |02 is vertically penetrated by a die aperture I which.. in its lateral location, extends along and inward from the line of left abutment |09. Within said die aperture ill reciprocates punch ||2 whose`v cross-section is similar to that of die aperture l although necessarily a bit smaller, and whosef lower or cutting edge i3 shears in cooperation with the edge formed by the intersection of diel aperture HI with lower side |08 of throat |07.. Punch ||2 is depressed by the cam pressure of' the eccentric rod mit bearing against its upper surface, resulting from turning handle 0 When such pressure is released, it is raised to its origi nal position above throat |01 by compression spring i |23 pressing at its lower end against seat ||5 in the upper surface of block |02, and lifting punch i l2 by pressure of its upper end against key iii afxed in and protruding sideward from the punch i 2.

Spring lid, while of suicient strength to raise punch lid when not subject to the cam force referred to, nevertheless can be depressed by a relatively slight amount of force. Accordingly, on loosening thumb screw |05, entire notcher assemblies may be removed from under eccentric rod |00. Similarly additional notching cutters cutting notches of a variety of forms may be added and so spaced along outer notcher support bar 013 as to yield any desired notch spacing. Although in Fig. 1 I have shown an arrangement of notchers suitable for notching transition duct members, for notching straight sections of rectangular ducts, notchers are re- (quired asshown in Fig. 5. Of these, the intermediate three are simple V-notch cutters, to mark bend lines and permit the necessary bending at ends, while the end notches shown are developed in order to permit entry into such seam machines as the widely used Pittsburgh machine. Another function of said end notches is that sheets of greater width than desired may be first notched in the usual manner, that is, notching the left end, turning the sheet over right to left, and notching the other end. 'Ihe notches cut by the most forward notcher are then used as a guide for shearing the sheet to the desired width, by pulling the sheet forward and centering it until said notches reach the forward shear guide angle 28', holding it with the toggle clamps 6| and shearing with rolling shear 34.

Referring now to Figs. 1 and 1l, stop base block H6, like notcher block |02, is equipped with -a square-cut keyway |04', thumb screw |05 and tapped hole |06' extending sideward into said keyway. Secured near its upper end and approximately at the same height as table plate '2| is forward-extending stud which penetrates the horizontal slot ||8 in gage bar H9, adjustably secured thereto by wing nut |20. The ,inner surface |2| of said gage bar ||9 extends :from a point somewhat above to a point somewhat below the level of table plate 2|, and thus serves as an abutment for sheets of metal placed on said table plate and moved to and beyond the left edge thereof.

Fig. l shows two such abutments in place with the jig set up for notching transition sheets. It is apparent that, for notching rectangular sheets as shown in Fig. 5, no such abutments are required, for the left abutments |09 of the throats |01 of the several notching cutters adequately serve this function.

The problem of notching the obliquely-cut, bisymmetric transition sheets such as shown in Fig. 4, is somewhat different. Because of their oblique angles, abutment strip 24 at the rear of table plate 2| cannot be employed as a guide for notching them.

Reference has heretofore been made to the use of abutment bars 13, illustrated in Fig. l, for shearing such sheets at the right end of the device. One such abutment bar is shown in Fig. 1 at the left end of the jig, in place for use as a notching guide for such bi-symmetric, obliquely-cut sheets, one of which being there shown in phantom lines. The angularity of such abutment bar I3 has been set to correspond with the angularity of the sides of the sheet to be notched. Two notcher blocks |02 are shown affixed so that one is adjacent either side of said abutment bar; and outward of each said notcher block is affixed a stop base block ||6 with its gage bar ||9 in place. On examination of Fig. l, it will be apparent that the four corners of such obliquely-cut bi-symmetric sheets will be notched with precision in the following manner: keeping one side of the sheet up, it is fed (with its parallel sides at all times parallel to the left edge of table plate 2|) first into the notcher on one side of the abutment bar i3 and then into the other, meantime turning it 180. The sheet is then turned over so that the other side is up, and said steps repeated.

In the manner hereinabove described, my invention provides a simple and practical means and method whereby rectangular duct sheet may be squarely sheared along two adjacent edges,

gang-notched at one end, turned over and symmt'rcally gang-notched at the other, with speed and exactness as is required for the mass production of interchangeable ducts. The adjustments for varying size and proportion of the ducts are simple, and require no further comment. As for the automatic layout and notching of the transition sheets, the same device provides for shearing strips, shearing these into by-symmetric rectilinear pieces, and notching each of their four corners precisely and speedily. The linear and protractor scales, the variable and adaptable abutment means, the rolling shears, adjustable notchers and all other parts cooperate to achieve these unique results.

Again mentioning the shear means provided, unique results have been achieved by their ability to shear sheets along the entire length and width of the table plate 2|. Unlike shears of the type mounted on a yoke or bght accommodating a limited width of sheet, the present shear means may be used for shearing sheets of any width, regardless of the distance from the edge of the uncut sheet; and subject only to the limitation of width of the table plate 2|.

Referring once more to Fig. '7, in service, it will be found that wear occurs along the cutting edges of upper shearing disc 40 and lower shearing disc 53. In order to take up the wear and provide for grinding back, as well as for adjustment for varying sheet metal thicknesses, thread-ended pins 52 are made in a novel manner hereinafter described. Each pin 52 has a central bearing stem |22 in which threads |23 are cut at one end, mating with a correspondingly tapped hole |24 in the carrier structure. At the opposite side of said bearing stem |22 is a diametrically enlarged thread-ended bearing portion |25 equipped with internal wrenching socket |26. Its bearing portion is seated in a drilled hole |21 in the carrier structure. The demarcation of said diametrically enlarged portion |25 from central bearing stem |22 forms shoulder |28, which is adapted to bear against the end A of the cutting discs tubular stem 43. From the drawing, it is apparent that by screwing said pins 52 by their internal wrenching sockets |26, the upper and lov/er shearing discs 40 and 53 may be advanced toward each other (no other adjustment being required) and secured by tightening lock nuts |29, provided the whole faces of disc cutters 40, 53 are ground down.

It should be understood that changes and modifications in the form, construction, arrangement, and combination of the several parts of the punching and cutting devices, including duct gages, may be made and substituted for those herein shown and described without departing from the nature and principle of the present invention.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. The method of shearing sheet metal strips into bisymmetrical oblique-angled pieces, comprising fixing to a table a pair of abutment bars parallel to each other at sufficient distance to accommodate and guide between them the strip to be sheared and at such angle to the table edge as is desired to be cut, advancing said strip across said table edge, shearing along said table edge, turning said strip over, replacing it between said parallel abutment bars, advancing it such distance that the said table edge marks the desired line of cut, aiiixing against the rst-sheared edge a laterallyand angularly-adjustable gage,

shearing along said table edge, removing the piece so sheared, turning over the remainder of said strip, replacing it between said parallel abutment bars, advancing the last-sheared edge against said gage, and repeating the ve steps last mentioned until said strip is utilized as fully as is possible.

2. The method of laying out and cutting sheet metal for forming straight sections of interchangeable rectangular ducts, `'comprising placing a sheet of sheet metal on a table and aligning it against a scaled rear abutment so that the eX- cess length of said sheet overhangs an edge of said table, shearing along said edge, adjusting along the opposite edge of said table a plurality or notchers, including one notcher adapted to mark the width desired, inserting one edge of said sheet into said notchers, maintaining said sheet abutting against said scaled rear abutment, actuating said notchers, removing the said sheet therefrom, turning it over and inserting the opposite end into said notchers, maintaining said sheet abutting against said rear abutment, actuating said notchers, removing said sheet therefrom to a position wherein the two notchers marking the desired width of sheet align with the cutting line of a shear, and shearing said sheet along a line between said two notches.

3. The method of shearing a sheet inetal strip into a number of like loi-symmetrical obliqueangled pieces, utilizing a work table having a rectilinear shear, an abutment bar adjustably mounted to the table surface, and a remote gage spaced outward from the line of shear, comprising the steps of securing the abutment bar to the table surface at the desired oblique angle to the line of shear, placing the sheet metal strip on the table with its rst side down., its iirst edge against the abutment bar, and with one end of the strip projecting across and outward of the line of shear, shearing the projecting end from the stripl and discarding said end, turning the strip over onto its second side and placing its second edge against id the abutment bar and advancing the strip across' the line of shear such distance that the portion projecting beyond the line of shear is a bi-symmetrioal oblique-angled piece of the size desired, afxing the remote gage against the newly sheared end and securing it in reference to the work table, again shearing the strip, removing the oblique-angled piece so sheared from the strip, turning the remainder of the strip onto its first side with its rst edge against the abutment bar and advancing its newly sheared end against the remote gage, again shearing the strip and removing the piece so sheared, and continuing the steps of turning the stripy over, aligning it with the abutment bar, advancing its newly sheared end against the remote gage, and shearing, until the desired number of pieces is formed or the strip is exhausted.

CHARLES FRANK ENGEL.

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